How Safe is Spray-Foam Insulation?

Q.I've heard that
polyurethane spray-foam insulation may contain
penta-BDE, a chemical that is called a "toxic flame
retardant" by the EPA and has been banned in some
states. How much of a risk does this chemical cause for
the installer and the homeowner, and are there
alternatives?

A.Mason Knowles, a former
director of the Spray Polyurethane Foam Alliance
and an industry consultant, responds:
Penta-BDE (pentabromodiphenyl ether) is one of a
family of brominated fire retardants that also
includes deca-BDE and octa-BDE. Penta-BDE was once
commonly used in the flexible-foam industry for car
seats, furniture, and plastic circuit boards.
However, its short shelf life made it ill-suited
for SPF systems, which may not be sprayed until
several months after they’ve been blended.
According to the manufacturers I’ve spoken
with, penta-BDE has seldom — if ever
— been used in residential spray foam.

A concern with penta-BDE is that it accumulates
in body fat; it first gained attention when
dramatically elevated levels of the chemical were
found in the breast milk of nursing mothers.
According to the Agency for Toxic Substances and
Disease Registry, nothing definite is known about
the health effects of penta-BDE on humans, though
studies with lab animals suggest it may affect the
liver, the thyroid, and neurobehavioral
development. Even though it’s not
specifically identified as a carcinogen, penta-BDE
is no longer manufactured in the U.S., and some
states and countries have passed measures
regulating its use or banning it altogether, as a
precautionary measure.

While deca-BDE and a few other brominated fire
retardants are still being manufactured,
they’re gradually being phased out in
favor of phosphorus-based flame retardants, which
don’t form dioxins or furans when
they’re burned. Probably the two
retardants most commonly used in polyurethane spray
foams are Tris(2-chloro-1-methylethyl)phosphate
(TCPP/TMCP), which contains both chlorine and
phosphorus, and halogen-free
resorcinol-bis(diphenyl phosphate), or RDP. Because
manufacturers are allowed to substitute one
retardant for another in their formulas without
having to retest, it’s difficult to know
exactly which manufacturer uses which flame
retardant, but outside of normal precautions for
workers who handle the bulk materials, I
haven’t heard of any health issues
concerning these types of retardants.